As a patient loses blood during surgery, the blood is often replaced by transfusion to the patient. Conventionally, this requires that a supply of blood be available that is crossmatched with the patient's own blood to be certain that the two are compatible. The problems of processing blood from donors, of storing that blood and of crossmatching that blood with the patient are substantially circumvented by the use of autologous blood transfusion techniques. By such a technique, the patient's own blood, lost through a wound or surgical incision, is collected and returned to the patient.
Typically the patient's blood is collected from the surgical site by a suction wand. The collected blood may be contaminated by bone particles, fat, saline irrigation solutions and the like. To prevent return of those contaminants to the patient, the autologous transfusion systems clean the blood by separating out the components and contaminants in the centrifuge, concentrating the red blood cells, and washing the red blood cells in the centrifuge. The washed red blood cells are then returned to the patient.
Prior to delivery to the cell salvage system, the blood taken from the patient is collected in a reservoir. Typically that reservoir is a transparent, rigid plastic sterilized disposable container having a filter therein. The reservoir is connected at one end to a vacuum source and at the other end to the suction wand. The blood is suctioned into the reservoir through one or more input ports located at the top of the reservoir and is delivered to the cell salvage system through an outlet port at the bottom. A filter element is positioned between the inlet and outlet to remove bone fragments and the like from the blood.
Current operating procedures for autologous blood recovery systems required the operator to visually monitor the volume of blood fluid as it is collected by the suction wand and stored in the reservoir. The operator then initiates the cell salvage process when sufficient volume of blood is observed to be present in the reservoir. When this volume is processed the cell salvage process is stopped. The operator must then wait and observe the volume level of blood collected by the wand into the reservoir and reinitiate processing when the predetermined level is obtained. A need exists for automating this time-consuming procedure and to eliminate the human factor which requires the diligence of a user to watch the reservoir volume to prevent overflow.